Negative permittivity of ZnO thin films prepared from aluminum and gallium doped ceramics via pulsed-laser deposition

Aluminum and gallium doped zinc oxide thin films with negative dielectric permittivity in the near infrared spectral range are grown by pulsed laser deposition. Composite ceramics comprising ZnO and secondary phase Al2O3 or Ga2O3 are employed as targets for laser ablation. Films deposited on glass from dense and small-grained ceramic targets show optical transmission larger than 70 % in the visible and reveal an onset of metallic reflectivity in the near infrared at 1100 nm and a crossover to a negative real part of the permittivity at approximately 1500 nm. In Both authors (M.A.B. and G.S.) contributed equally to this study. M.A. Bodea · G. Sbarcea · T.A. Klar · J.D. Pedarnig ( ) Institute of Applied Physics, Johannes Kepler University Linz, 4040 Linz, Austria e-mail: [email protected] url: http://www.jku.at/applphys G. Sbarcea University Politehnica of Bucharest, 060042 Bucharest, Romania G. Sbarcea National Institute for Research and Development in Electrical Engineering ICPE-CA, 030138 Bucharest, Romania G.V. Naik · A. Boltasseva School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA A. Boltasseva DTU Fotonik, Technical University of Denmark, Kgs. Lyngby 2800, Denmark A. Boltasseva Erlangen Graduate School of Advanced Optical Technologies (SAOT), University Erlangen Nürnberg, 91052 Erlangen, Germany comparison to noble metals, doped ZnO shows substantially smaller losses in the near infrared.